Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Robots are currently being used in numerous applications and in numerous ways. A few examples of their utilization may be found in industrial applications where robots are used to perform repetitious or strenuous tasks and in medical applications sometimes to assist a surgeon to perform surgery. For all their proliferation, robots are still limited in various ways. One limitation which characterizes many robots is that they can only operate for a certain amount of time with a given battery size. One cause of this limitation is due to the losses that occur in the process of converting electrical energy to mechanical outputs. Improving the efficiency of conversion would then directly lead to longer operation time given a battery size. In addition, the concepts to improve efficiency in mobile robots may be advantageous on stationary wall-powered robots as well. For example, improved efficiency may lead to smaller motors thus leading to more compact design. Yet another limitation that also characterizes many robots is that they are often designed for the worst case load and speed conditions, making them big and bulky. This is because a robot designer generally picks a set transmission ratio for each actuator. Currently available variable transmissions, such as the nuVinci or belt-driven conical continuously variable transmissions used in larger vehicles, are generally less efficient and much heavier and bulkier than single-speed options available to robot designers. Theoretically, smaller motors or actuators could be used if variable transmissions were comparable in efficiency, size, and weight. Designing a robot that can quickly adapt to changing load conditions and operate with high efficiency would be desirable.